Doctor Who Seawson 4 Episode 1 Partners in Crime

Doctor Who Partners in Crime 1/13

The episode primarily focuses upon Donna Noble, a previous companion who appeared in "The Runaway Bride". Since her last encounter with the Doctor, she has had a major change in personality. She became disenchanted with normal life, and began searching for the Doctor, regretting declining his invitation to travel in the TARDIS. She also starts believing conspiracy theories—apart from one about "the Titanic flying over Buckingham Palace on Christmas Day". She confides her regrets in her grandfather Wilfred Mott, an amateur astronomer who met the Doctor shortly before the episode's events.

The episode's events concern Adipose Industries, who are marketing a diet pill to London's population with the slogan "the fat just walks away". Believing the treatment to be otherworldly, the Doctor and Donna investigate separately, and find that the slogan is literal—the pills use latent body fat to parthenogenetically create the Adipose, small white aliens. In an emergency, multiple Adipose can spawn by using all of the host's organic tissue. When the Doctor and Donna meet, they are confronted by Miss Foster, an alien who is exploiting Britain's overweight population to create the Adipose for the Adiposian First Family.

Foster accelerates her plans, feeling threatened by the Doctor's invocation of galactic law and fearing he may "inform the Shadow Proclamation", an intergalactic code and council.Throughout London, the Adipose begin to spawn, soon numbering several thousand, and make their way to Adipose Industries, though the Doctor and Donna are able to prevent full parthenogenesis occurring. The Adiposian First Family use their spaceship to collect the Adipose, but kill Foster to hide any evidence they used Earth illegally. The Doctor defers from killing the Adipose because they are children; Donna notes that Martha, his previous companion, made him more human, citing his infanticide of the Racnoss in their previous encounter.

At the end of the episode, Donna accepts an offer to travel in the TARDIS. She makes a detour to leave her car keys for her mother Sylvia, and asks a blonde woman to help Sylvia find the keys. The woman turns towards the camera, revealing her to be Rose Tyler, and fades as she walks away from the area. It then shows the TARDIS flying through the sky. Wilf spots it and sees Donna waving at him through his telescope.